2003/05/12 by Eran O. Ofek, E. O. Ofek, Dan Maoz · 3 citations
Physics and Astronomy · #Adaptive optics and wavefront sensing #Galaxies: Formation, Evolution, Phenomena #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/376903
published as Astrophys.J. 594 (2003) 101-106 · 7 pages, ApJ, in press
arxiv created 2003/05/12 · openalex publication_date 2003/08/20 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
We have measured the time delay between the two images of the gravitationally lensed quasar HE 1104-1805 by combining observations made with the Wise Observatory 1 m telescope and published observations of this system by Schechter et al., spanning a total of 5 years, from 1997 to 2002. Based on a variety of techniques, we find that the best-fit time delay is -161 days. The 68% and 95% confidence intervals include the systematic errors due to an observed component of uncorrelated variability between images. The delay is shorter than predicted by simple models and may indicate a large external shear or a large value of the Hubble parameter, h > 0.75 (95% confidence). The residual light curve between the two images shows a long-term trend of ~0.04 mag yr -1 , presumably the result of microlensing by stars in the lens galaxy, but also short-timescale (~1 month) variability with a mean amplitude of about 0.07 mag.